title: Evidence for the functional compartmentalization of the temporalis muscle: a 3-dimensional study of innervation.
abstract: OBJECTIVE
  The temporalis muscle is commonly used for functional transfer. It is architecturally complex, but few studies have examined its intramuscular innervation and none has used 3-dimensional modeling techniques. Understanding neuromuscular compartmentalization may allow the design of local muscle transfers to minimize donor-site morbidity. The purpose of the present study was to document the intramuscular innervation patterns throughout the volume of the temporalis muscle and define functional units within the muscle.
  
  
  METHODS
  In 10 formalin-embalmed cadaveric specimens, the foramen ovale was exposed and the branches of the mandibular nerve were identified. Each branch was digitized in short segments extramuscularly and intramuscularly. Three-dimensional models were reconstructed from the digitized data using Maya software, and the innervation patterns were documented.
  
  
  RESULTS
  The temporalis muscle was found to have superior and inferior parts that were further grouped by innervation into regions, with each receiving its innervation from 1 primary nerve. The nerves originated directly from the mandibular nerve, except in 3 specimens, where the posterior deep temporal nerve arose from the masseteric nerve.
  
  
  CONCLUSIONS
  These results provide a detailed mapping of innervation patterns and suggest there are at least 5 functional compartments. Each of these has the capacity for selective activation, 3 of which have clinical value. These findings may allow for decreased donor-site morbidity and more functionally sophisticated designs in clinical practice.
authors.affiliation: Division of Anatomy, Department of Surgery, University of Toronto, Toronto, Ontario, Canada. ychan059@uottawa.ca
authors.forename: Youjin
authors.initials: Y
authors.lastname: Chang
authors.forename: David
authors.initials: D
authors.lastname: Cantelmi
authors.forename: Jonathan J
authors.initials: JJ
authors.lastname: Wisco
authors.forename: Adel
authors.initials: A
authors.lastname: Fattah
authors.forename: Alan G
authors.initials: AG
authors.lastname: Hannam
authors.forename: Anne M
authors.initials: AM
authors.lastname: Agur
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D004210:Dissection; D005205:Fascia / Q000294:innervation; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008036:Lingual Nerve / Q000033:anatomy & histology; D008297:Male; D008340:Mandibular Nerve / Q000033:anatomy & histology; D008406:Masseter Muscle / Q000294:innervation; D008875:Middle Aged; D009469:Neuromuscular Junction / Q000033:anatomy & histology; D013524:Surgical Flaps / Q000294:innervation; D013703:Temporal Muscle / Q000294:innervation*; D055815:Young Adult